Abstract:

Introduction: Autoimmune blistering dermatoses can be difficult to differentiate histologically. IgG4 autoantibodies are hypothesized to contribute to blister formation and collagen type IV (col-IV) has distinct localization patterns in subepidermal blistering diseases. The goal of this study is to compare immunohistochemical characteristics between autoimmune blistering dermatoses. Methods: We compared IgG4 immunoreactivity and the location of col-IV in complete subepidermal blisters among 96 patients across 12 types of blistering diseases. IgG4 was measured using a semi-quantitative analysis of intensity (0-3+) and % positive keratinocytes and plasma cells. Results: Bullous pemphigoid (45%), dermatitis herpetiformis (21%), and pemphigus vulgaris (13%) were the most common diagnoses. Overall, 25% of the sample demonstrated IgG4 reactivity and IgG4 was significantly associated with disease type (p=0.004). IgG4 was present in keratinocytes in 4/12 cases of pemphigus vulgaris (33%) and 8/43 cases of bullous pemphigoid (19%). IgG4 stained plasma cells in 15/43 cases of bullous pemphigoid (35%), 2/4 cases of pemphigus foliaceus (50%), and 5/12 cases of pemphigus vulgaris (42%). The localization of col-IV was significantly associated with the type of blistering disease (p=0.003). The base was the most common location for col-IV and was found to be present in all cases of bullous pemphigoid, linear IgA dermatosis, paraneoplastic pemphigus, and pemphigoid gestationis. Contrastingly, bullous lupus had 2/3 cases (67%) with col-IV on the roof of the blister. Conclusion: Our findings suggest that IgG4 autoantibodies are present and likely relevant to the pathogenesis of both pemphigus vulgaris and bullous pemphigoid. Our sample showed a predominance of IgG4 activity in pemphigus when compared to pemphigoid. Col-IV was visualized at the base for most blisters. It can be a useful biomarker to differentiate bullous lupus, which characteristically had col-IV on the blister roof.

Financial Disclosure:
No current or relevant financial relationships exist.

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Itohan Omorodion, MPH

Biography